Biol 189 Quiz 4

Front 1

dna to be accepted as the genetic material needs

Back 1

-be present in cell nucleus and in chromosomes
-doubles in cell cycle (s phase)
-is twice as abundant in diploid cells
-has same pattern of transmission as its genetic information (fertilization)

Front 2

dna chemical composition

Back 2

-is a polymer of nucleotides: deoxyribose + phosphate group + nitrogen base (by covalent bonds)
-bases: purines-- adenine and guanine
pyrimidines-- cytosine and thymine (by hydrogen bonds)

Front 3

chargaff's rule

Back 3

-the abundance of purines = the abundance of pyrimidines

Front 4

francis crick and james watson and rosalin franklin

Back 4

-Rosalin franklin uses xray for helical dna stands
-strands are anti-parallel. 5-3, 3-5 carbon sugar
-Crick and watson suggested that nucleotide bases are on interior of 2 strands with a sugar-phosphate backbone on outside

Front 5

dna functions

Back 5

-storage of genetic info-- millions of nucleotides
-precise replication during cell division-- by completing base pairing
-susceptibility to mutations-- a change in information
-expression of coded information as the phenotype-- nucleotide sequence is transcribed into rna and determines sequence of amino acid in proteins

Front 6

2 steps in dna replication semi conservative

Back 6

-double helix is unwound, making 2 template strands available for new base pairing
-new nucleotides form base pairs with template strands and linked together by phosphodiester bonds
-template is read in the 3-5 direction
-semi conservative because half is of parental in dna

Front 7

origins of replication (ori)

Back 7

-where replications begins
-2 strands are separated, opening up replication bubble
-proceeds in both direction from each origin, until entire molecule is copied

Front 8

replication fork

Back 8

-at end of each replication bubble
-y shaped region where new dna strands are elongating

Front 9

helicases

Back 9

-enzymes that untwist double helix at replication fork
-breaks hydrogen bonds

Front 10

single-strand binding protein

Back 10

-binds to and stabilizes single-stranded dna until it can be used as a template

Front 11

topoisomerase

Back 11

-corrects "overwinding" ahead of replication forks by breaking, swiveling, and rejoining dna strands

Front 12

dna polymerases

Back 12

-enyzmes that catalyzes the elongation of new dna at replication fork
-most polymerases require primer and dna template strand (adding nucleotide)

Front 13

when a single replication fork opens up in one direction, 2 dna strands are

Back 13

-antiparallel- the 3 end of one strand is paired with the 5 end of other
-dna replicates in 5-3 direction

Front 14

lagging strand

Back 14

-to elongate other new stand, dna polymerase must work in direction away from replication fork

Front 15

okazaki fragments

Back 15

-lagging strand is synthesized as series of fragments which are joined together by dna ligase

Front 16

telomeres

Back 16

-repetitive sequences at ends of eukaryotic chromosomes
-prevent chromosomes ends from being joined together by dna repair system

Front 17

telomerase

Back 17

-acts as template for telomeric dna sequence
-is lost over time in most cells, but not in continuously dividing cells like bone marrow and gametes

Front 18

cells have 2 major repair mechanisms

Back 18

-proofreading-- as dna polymerase adds nucleotides, it has proofreading function and if bases are paired incorrectly, the nucleotide is removed
-mismatch repair-- after replication, other proteins scan for mismatched bases missed in proofreading, and replace them with correct ones

Front 19

mutations

Back 19

-changes in nucleotide sequence of dna that are passed on from 1 cell, or organism, to another

Front 20

somatic mutations

Back 20

-occur in somatic cells, passed on by mitosis but not to sexually produced offspring

Front 21

germ line mutations

Back 21

-occur in germ line cells that give rise to gametes. a gamete passes a mutation on at fertilization

Front 22

mutation are caused in 2 ways:

Back 22

-spontaneous mutations-- occur with no outside influence, and are permanent
-induced mutations-- due to an outside agent, a mutagen (ie radiation, cigarettes, or liquor)

Front 23

induced mutation examples

Back 23

-chemicals can alter nucleotide bases
-some chemical add other groups to bases (ie. benzopyrene adds group to guanine and prevents pairing)
-ionizing radiation, such as x rays, creates free radicals than change bases, break sugar phosphate bonds
-uv radiation (from sun or tanning bed) is absorbed by thymine, disrupts dna replication

Front 24

protein synthesis occurs in 2 steps

Back 24

-transcription
-translation

Front 25

transcription

Back 25

-copies information from dna sequence (a gene) to complimentary rna sequence
-only in nucleus
-needs dna template, nucleosides, and enzyme rna polymerase (rna = u-a, c-g)
-final product mRNA

Front 26

translation

Back 26

-converts rna sequence into amino acid sequence of polypeptide
-in cytosol

Front 27

3 kinds of rna in protein synthesis

Back 27

-messenger rna (mRNA)
-ribosomal rna (rRNA)
-transfer rna (tRNA)

Front 28

messenger rna

Back 28

-in transcription--carries copy of dna sequence to site of protein synthesis at ribosome

Front 29

ribosomal rna

Back 29

-in translation--catalyzes peptide bonds between amino acids

Front 30

transfer rna

Back 30

-in translation
-mediates between mRNA and protein--carries amino acids for polypeptide assembly

Front 31

formation of specific rna from a specific dna sequence requires

Back 31

-dna template for base pairing
-nucleosides (ATP,GTP,CTP,UTP)
-an rna polymerase enzyme

Front 32

transcription occurs in 3 phases

Back 32

-initiation
-elongation
-termination

Front 33

transcription initiation

Back 33

-requires promoter that tell rna polymerase where to start trancription and which strand of dna to transcribe

Front 34

elongation transcription

Back 34

-make long by adding bases to pre mRNA

Front 35

transcription termination

Back 35

-removal of intron keep exon
-coding regions

Front 36

coding regions

Back 36

-sequences of dna molecule that are expressed as proteins

Front 37

introns

Back 37

-eukaryotic genes may have noncoding sequences
-intervening regions

Front 38

exons

Back 38

-information we need
-coding sequence
-expressed regions

Front 39

dna synthesis recipe

Back 39

1.dna
2. semi conservative (half from parents)
3.enzymes
-3.1-- helicase to untwist dna
-3.2-- single strand for binding protein
-3.3-- topoisomerase prevents overwinding
-3.4-- polymerase adds nucleotides to leading strand and lagging stand (= okaski fragments)
---dna polymerase and ligase (glue)